Engineering plastics such as poly(arylene sulfide) resins are excellent polymers having good thermal stability, chemical resistance, flame resistance, and electrical insulation properties. These physical properties make them useful as, for example, coatings for pipes, tanks, or pumps, in manufacturing extruded articles, films, sheets, or fibers, and in injection molded products for electronic or electrical applications.
Generally, these polymers, when newly made, have a pleasant and attractive appearance due to extremely low coloration. They are, however, known to have a very high absorption of light in the ultraviolet (hereinafter referred to as UV) region. Upon being exposed to solar or UV rays, these polymers darken in color. Furthermore, absorption of UV light may result in a decrease in some mechanical properties of the polymers.
The common method of stabilizing a polymer against light is by mixing it with a protective agent. In comparison to coating finished products (films and fibers) with stabilizers or incorporation of photostabilizing functionalities into the polymer, the method based on bulk addition of a protective agent is usually straightforward and can be technologically simple. To achieve optimal action without seriously affecting desired properties of a given polymer, a great deal of care, however, is called for in selecting the type and amount of a compatible additive useful as a protective agent.
Certain metals, metal compounds (including oxides, carbonates and sulfides), transition metal complexes, organotin azolides, pyrene derivatives, non-sulfur-containing hydroxyphenylbenzotriazole derivatives and special aniline-nitrobenzene dyes (nigrosins) have been claimed to improve UV stability of polymers and/or reduce radical formation in polymers. For example, non-sulfur-containing hydroxyphenylbenzotriazole derivatives when added to a poly(arylene sulfide) polymer work well as stabilizers to reduce the deleterious effects of ultraviolet exposure upon the polymer. Unfortunately, the high melt processing temperatures of the polymer lead to loss of these stabilizers through evaporation. The degree of UV light stabilization afforded to the polymer by these known non-sulfur-containing hydroxyphenylbenzotriazole derivatives is thereby appreciably limited.
Therefore, it would be a significant contribution to the art if a new hydroxyphenylbenzotriazole derivative that is less volatile at the temperatures used to process tile polymers and affords a higher degree of protection against UV light can be developed.